Optimization of Preparation of Iron-chelating Peptides from Antarctic Krill by Response Surface Methodology and Its Physicochemical Properties

Iron-chelating peptide was prepared from Antarctic krill by enzymatic hydrolysis. With iron-chelating rate as the main indicator,and the degree of hydrolysis(DH)as indicator,the hydrolysis process was optimized using one-factor-at-a-time method and response surface methodology(RSM). The physicochemical properties of hydrolysates obtained under the optimized conditions were analyzed. Results showed that Alcalase 2.4 L was the suitable enzyme. The optimal hydrolysis conditions were as follows:Hydrolysis temperature 57.6 ℃,enzyme/substrate ratio 5.5%,pH8.8,hydrolysis time 5 h. The actual iron-chelating rate of the peptides prepared under the(optimized condition was 77.77%±0.72%,DH was 23.22%±0.16%,which was in good agreement with the predicted value. Amino acid composition analysis showed that the Antarctic krill iron-chelating peptides(AKIP)had good iron-chelating sites. The relative molecular weight of AKIP was amount of 180~1000 Da and accounted for 89.28%. In vitro antioxidant experiments showed that,AKIP had good scavenging capacity for DPPH free radicals and hydroxyl free radicals(IC₅₀ was 1.92 and 2.09 mg/mL,respectively),and showed a good dose-effect relationship. This study AKIP had a certain value in food-protein derived chelating peptides and natural antioxidants fields.